一、通常数据库操作会创建一个DAO类
public DBDao(Context context){
DBOpenHelper dbOpenHelper = new DBOpenHelper(context);
//writable加锁操作数据库
//dbOpenHelper.getReadableDatabase();
//dbOpenHelper.getWritableDatabase();
}
/**
* 增
*/
public void add(String name){
SQLiteDatabase db = dbOpenHelper.getWriteDatabase();
if(db.isOpen()){
db.execSQL("insert into book(name) values(?)",new Object[]{name});
db.close();
}
}
/**
* 删
*/
public void delete(String name){
SQLiteDatabase db = dbOpenHelper.getWriteDatabase();
if(db.isOpen()){
db.execSQL("delete from book where name=?",new Object[]{name});
db.close();
}
}
/**
* 改
*/
public void update(String name,String newname){
SQLiteDatabase db = dbOpenHelper.getWriteDatabase();
if(db.isOpen()){
db.execSQL("update book set name=?,value=? where name=?",new Objec[]{name,newname});
db.close();
}
}
/**
* 查
*/
public void find(String name){
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
if(db.isOpen()){
//返回结果集
Cursor cursor = db.rawQuery("select * from book where name=?",new String[]{name});
if(cursor.moveToFirst()){
//name在行中第几列
int index = cursor.getColumnIndex("name");
cursor.getString(index);
}
cursor.close();
db.close();
}
}
public List<Book> findAllList(){
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
if(db.isOpen()){
Cursor cursor = db.rawQuery("select * from book",null);
while(cursor.moveToNext()){
int index = cursor.getColumnIndex("name");
cursor.getString(index);
}
cursor.close();
db.close();
}
}